Organocatalytic asymmetric aldol reaction of ketones with isatins: straightforward stereoselective synthesis of 3-alkyl-3-hydroxyindolin-2-ones

An efficient asymmetric aldol condensation of ketones with isatins has been developed using an l-proline-derived bifunctional organocatalyst. This strategy allows the enantioselective synthesis of a variety of 3-alkyl-3-hydroxyindolin-2-ones with a stereogenic quaternary carbon center in excellent yields with good to excellent enantiomeric excess. The method has been applied to the enatioselective synthesis of (S)-convolutamydine A successfully.